It is often necessary to make a mold of a foot for the purpose of making a prosthetic device or insert for a shoe. One conventional technique uses Plaster of Paris or similar material, usually combined with a wrapping material, to form an impression of the foot from which a positive replica can be made. This is a slow process, is generally messy and the cast is removed only with careful, tedious effort. In other approaches, wax or various plastics are used by applying heat to them in one step or device and then carrying out the forming in a second. In applications using plaster, wax or cork, if the mold is crushed it cannot be recovered but must be re-molded. Some molding techniques require pressure levels while molding, which temporarily deform the foot and produce unsuitable reproductions.